Assignment No – 4
Acids, Bases and Salts
Que 31. While diluting the acid, why is it
recommended that acids should be added to water and not water to acid?
Que 32. Write the composition of baking
powder. What will happen if tartaric acid is not added to it?
Que 33. A student working in the laboratory added some water to a syrupy
liquid taken in a tube. The tube immediately cracked and the liquid which
escaped out of it, produced blisters on the skin of the student. What actually happened?
Que 34. A compound X of sodium is commonly
used for making crispy pakoras. It is also
used for curing acidity in the stomach. Identify ‘X’. What is its formula?
State the reaction that takes place when it is
heated.
Que 35. Dry hydrogen chloride gas does not
turn blue litmus whereas hydrochloric acid
does. Give one reason.
Que 36. Why should curd and sour substances not be kept in brass and
copper vessels?
Que 37. Which gas is usually liberated when an acid reacts with a metal?
Illustrate with an example. How will you test for the presence of this gas?
Que 38. Metal compound A reacts with dilute hydrochloric acid to produce
effervescence. The gas evolved extinguishes a burning candle. Write a balanced
chemical equation for the reaction if one of the compounds formed is calcium
chloride.
Que 39. How is the concentration of hydroxide ions (OH−) affected
when excess base is dissolved in a solution of sodium hydroxide?
Que 40. Under what soil condition do you think a farmer would treat the soil of his fields with quick lime (calcium oxide) or slaked lime (calcium hydroxide) or chalk (calcium carbonate)?
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